Many-body correlations and excitonic effects in semiconductor spectroscopy

Kira, M.; Koch, S. W.

doi:10.1016/j.pquantelec.2006.12.002

Cited by 383 publications

(477 citation statements)

References 147 publications

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“…Using the cluster expansion to evaluate B † s,s ′ ,α ( Q)B s,s ′ ,α ( Q) results in the additional Hartree-Fock term shown above 19,20 . The same extra term also shows up in the luminescence spectra of excitons 24 , and, as discussed below, this term results in a quadratic dependence of the capture rate on the exciton density at large exciton densities.…”

Section: Electron and Hole Capture Rates For Excitonsmentioning

confidence: 99%

“…We use the formalism developed by Kira and Koch 19,24 . When phase-space filling is taken into account, exciton eigenvalue equation in the relative co-ordinates becomes non-Hermitian (see the Appendix) and its solutions are expressed in terms of the left and the right eigenfunctions, φ L α,s,s ′ ( k, Q) and φ R α,s,s ′ ( k, Q), respectively.…”

Section: B Carrier Capture Times At High Exciton Densitiesmentioning

confidence: 99%

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Fast exciton annihilation by capture of electrons or holes by defects via Auger scattering in monolayer metal dichalcogenides

Wang¹,

Strait²,

Zhang³

et al. 2015

Phys. Rev. B

114

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The strong Coulomb interactions and the small exciton radii in two-dimensional metal dichalcogenides can result in very fast capture of electrons and holes of excitons by mid-gap defects from Auger processes. In the Auger processes considered here, an exciton is annihilated at a defect site with the capture of the electron (or the hole) by the defect and the hole (or the electron) is scattered to a high energy. In the case of excitons, the probability of finding an electron and a hole near each other is enhanced many folds compared to the case of free uncorrelated electrons and holes. Consequently, the rate of carrier capture by defects from Auger scattering for excitons in metal dichalcogenides can be 100-1000 times larger than for uncorrelated electrons and holes for carrier densities in the 10 11 -10 12 cm −2 range. We calculate the capture times of electrons and holes by defects and show that the capture times can be in the sub-picosecond to a few picoseconds range. The capture rates exhibit linear as well as quadratic dependence on the exciton density. These fast time scales agree well with the recent experimental observations and point to the importance of controlling defects in metal dichalcogenides for optoelectronic applications.

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Section: Electron and Hole Capture Rates For Excitonsmentioning

confidence: 99%

Section: B Carrier Capture Times At High Exciton Densitiesmentioning

confidence: 99%

Fast exciton annihilation by capture of electrons or holes by defects via Auger scattering in monolayer metal dichalcogenides

Wang¹,

Strait²,

Zhang³

et al. 2015

Phys. Rev. B

114

View full text Add to dashboard Cite

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“…Here, α m (ω) is the absorption coefficient of the molecular film in the presence of the semiconductor substrate and α sc (ω) that of the semiconductor in the presence of the molecular layer [28]. Both α m and α sc are proportional to their respective susceptibilities, which connect the incident field and the resulting macroscopic polarizations,…”

Section: Optical Spectramentioning

confidence: 99%

“…(7), the light-matter interaction is treated using a semiclassical approach in the dipole approximation [28] for both components of the hybrid material. The interaction strength is governed by the transition dipole moments d H L and d vc for the molecules and the substrate, respectively.…”

Section: A Hamilton Operatormentioning

confidence: 99%

“…(3) and (4), we now proceed to derive the equations of motion for the microscopic interband polarizations σ vc kk = a † k,v a k ,c in the semiconductor and the microscopic molecular polarization σ l,l H L = a † l,H a l ,L using the Heisenberg equation of motion. Focusing on the linear optical properties, the hierarchy problem arising from the correlation expansion of the Coulomb interaction is truncated at Hartree-Fock level [15,28,33,34], which yields an exact description of optical excitations in the linear optics limit [35]. Note that the molecular layer induces a spatially inhomogeneous charge distribution and thus we have to explicitly take into account polarizations with nonequal wave vectors k = k .…”

Section: Equations Of Motionmentioning

confidence: 99%

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Theory of optical excitations in dipole-coupled hybrid molecule-semiconductor layers: Coupling of a molecular resonance to semiconductor continuum states

et al. 2014

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We theoretically investigate the optical absorption of a hybrid system consisting of an organic molecular film on top of a semiconductor substrate. The electronic states of the isolated spatially separated constituents couple due to the Coulomb interaction of the optically induced charge carriers across the film-substrate interface. Focussing on the coupling of optical active molecular transitions to semiconductor continuum states, we find that the nonradiative dipole-dipole energy transfer causes the formation of coupled excitations, effectively reducing the excitation energy of the optical resonance in the molecular film and inducing a broadening of the associated absorption peak. In the framework of the Heisenberg equation of motion technique, we derive the Bloch equations for these hybrid systems. The input parameters for our model system of ladder-type quarterphenyl (L4P) molecules on the ZnO(1010) surface are taken from density functional theory calculations.

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